The Dutch government has started enforcing a ban on selling marijuana to foreign tourists in three southern provinces, sparking large protests against the new law, which authorities say will help reduce drug-related crime.

Some of the demonstrators openly smoked cannabis in the streets in several cities in protest of the law on Tuesday, while a number of the country's coffee shops, which are stores licensed to sell soft drugs, continued to sell in defiance of the ban.

The legislation, which will be implemented nationwide next year and only permits people with registered "weed passes" to purchase the drug, rolls back the Netherlands' traditionally lax policies by clamping down on the millions of "drug tourists" who flock every year to the country.

In the provinces of Limburg, North Brabant and Zealand, where the ban took effect, coffee shops are now only allowed to admit a maximum of 2,000 registered members, who must have a local address.

About two hundred protesters marched in the southern city of Maastricht, where a coffee shop was warned over violating the ban. In the city's main square, a few hundred demonstrators staged a sit-in and about 50 openly smoked joints there.

Maastricht's mayor, Onno Hoes, was presented with a petition signed by about 300 coffee shops and other outlets asking for the ban to be scrapped.

The city's Easy Going coffee shop closed its doors to all customers in protest.

Marc Josemans, head of Maastricht's coffee shop association, said that in recent weeks drug dealers from northern France, Belgium and eastern Europe had started plying their trade in the streets.

"Now this is totally new for Maastricht, we never had this problem, so actually we are creating more problems than we are solving," he said.

In the city of Tilburg, some coffee shops sold ready-rolled joints and sachets of weed to foreigners in open defiance of the new law.

Willem Vugs, proprietor of a coffee shop, told Reuters it was business as usual.

"We've been selling cannabis to anybody who comes, as normal," said Vugs, one of several coffee shop owners who wants to be brought before court so the ban can be tested.

"We are being forced to discriminate against foreigners."

The new law, passed by the Liberal-Christian Democrat coalition before it collapsed last month, was introduced in January.